path: root/src
diff options
authorRich Felker <>2014-07-16 20:44:22 -0400
committerRich Felker <>2014-07-16 20:44:22 -0400
commitc463e11eda8326aacee2ac1d516954a9574a2dcd (patch)
treed184ab694ab4e47712752bfb78601609676de9fb /src
parent781f26bc92b0710ac025fae3be42f5575468f1a5 (diff)
simplify __stdio_exit static linking logic
the purpose of this logic is to avoid linking __stdio_exit unless any stdio reads (which might require repositioning the file offset at exit time) or writes (which might require flushing at exit time) could have been performed. previously, exit called two wrapper functions for __stdio_exit named __flush_on_exit and __seek_on_exit. both of these functions actually performed both tasks (seek and flushing) by calling the underlying __stdio_exit. in order to avoid doing this twice, an overridable data object __towrite_used was used to cause __seek_on_exit to act as a nop when __towrite was linked. now, exit only makes one call, directly to __stdio_exit. this is satisfiable by a weak dummy definition in exit.c, but the real definition is pulled in by either __toread.c or __towrite.c through their referencing a symbol which is defined only in __stdio_exit.c.
Diffstat (limited to 'src')
4 files changed, 12 insertions, 16 deletions
diff --git a/src/exit/exit.c b/src/exit/exit.c
index 695bdc05..27fb3e29 100644
--- a/src/exit/exit.c
+++ b/src/exit/exit.c
@@ -6,10 +6,10 @@ static void dummy()
-/* __toread.c, __towrite.c, and atexit.c override these */
+/* atexit.c and __stdio_exit.c override these. the latter is linked
+ * as a consequence of linking either __toread.c or __towrite.c. */
weak_alias(dummy, __funcs_on_exit);
-weak_alias(dummy, __flush_on_exit);
-weak_alias(dummy, __seek_on_exit);
+weak_alias(dummy, __stdio_exit);
#ifndef SHARED
weak_alias(dummy, _fini);
@@ -28,8 +28,7 @@ _Noreturn void exit(int code)
- __flush_on_exit();
- __seek_on_exit();
+ __stdio_exit();
diff --git a/src/stdio/__stdio_exit.c b/src/stdio/__stdio_exit.c
index 0fb33234..e4380aaf 100644
--- a/src/stdio/__stdio_exit.c
+++ b/src/stdio/__stdio_exit.c
@@ -21,3 +21,5 @@ void __stdio_exit(void)
+weak_alias(__stdio_exit, __stdio_exit_needed);
diff --git a/src/stdio/__toread.c b/src/stdio/__toread.c
index 2e804f64..52624f3d 100644
--- a/src/stdio/__toread.c
+++ b/src/stdio/__toread.c
@@ -13,12 +13,9 @@ int __toread(FILE *f)
return 0;
-static const int dummy = 0;
-weak_alias(dummy, __towrite_used);
+void __stdio_exit_needed(void);
-void __stdio_exit(void);
-void __seek_on_exit()
+void __toread_needs_stdio_exit()
- if (!__towrite_used) __stdio_exit();
+ __stdio_exit_needed();
diff --git a/src/stdio/__towrite.c b/src/stdio/__towrite.c
index 380ea396..0a69d926 100644
--- a/src/stdio/__towrite.c
+++ b/src/stdio/__towrite.c
@@ -17,11 +17,9 @@ int __towrite(FILE *f)
return 0;
-const int __towrite_used = 1;
+void __stdio_exit_needed(void);
-void __stdio_exit(void);
-void __flush_on_exit()
+void __towrite_needs_stdio_exit()
- __stdio_exit();
+ __stdio_exit_needed();